Asthma and other respiratory diseases have long been treated by the inhalation of appropriate medicament Pulmonary inhalation is also becoming an attractive route of administration of medicaments that may be difficult to deliver orally such as proteins and peptides.
A widely used and convenient choice of pulmonary drug delivery has been the inhalation of medicament from an aerosol created by a pressurized metered dose inhaler (pMDI). pMDIs typically comprise a canister including a metered dose valve mounted on an aerosol container filled medicinal inhalation formulation and an actuator including a nasal- or mouthpiece. Suspension medicinal aerosol formulations used in canisters for pMDIs are typically prepared by dispersing, via e.g. a high shear mixer, particles of medicament in liquefied propellant(s), e.g. CFC propellant(s) and more recently non-CFC propellant(s), such as 1,1,1,2-tetrafluoroethane (HFA134a) and/or 1,1,1,2,3,3,3-heptafluoropropane (HFA227). If desired and/or deemed necessary, the formulation may comprise other components, such as excipients, co-solvents, and suspending aids.